Overall Survival with Durvalumab after Chemoradiotherapy in Stage III NSCLC

PD-1 and PD-L1 in cancer immunotherapy: clinical implications and future considerations

Programmed death-1 (PD-1) is a cell surface receptor that functions as a T cell checkpoint and plays a central role in regulating T cell exhaustion. Binding of PD-1 to its ligand, programmed death-ligand 1 (PD-L1), activates downstream signaling pathways and inhibits T cell activation. Moreover abnormally high PD-L1 expression on tumor cells and antigen-presenting cells in the tumor microenvironment mediates tumor immune escape, and the development of anti-PD-1/PD-L1 antibodies has recently become a hot topic in cancer immunotherapy. Here, we review the structure of PD-1 and PD-L1, the function of the PD-1/PD-L1 signaling pathway, the application of PD-1 or PD-L1 monoclonal antibodies and future directions for anti-PD-1/PD-L1 antibodies with combination therapies. Cancer immunotherapy using PD-1/PD-L1 immune checkpoint blockade may require more studies, and this approach may be curative for patients with many types of cancer in the future.

Patterns of care for stage III non-small cell lung cancer in Australia

Stage III non-small cell lung cancer (NSCLC) makes up a third of all NSCLC cases and is potentially curable. Despite this 5-year survival rates remain between 15% and 20% with chemoradiation treatment alone given with curative intent. With the recent exciting breakthroughs in immunotherapy use (durvalumab) for stage III NSCLC, further improvements in patient survival can be expected. Most patients with stage III NSCLC present initially to their general practitioner (GP). The recommended time from GP referral to first specialist appointment is less than 14 days with treatment initiated within 42 days. Our review found that there is a shortfall in meeting these recommendations, however a number of initiatives have been established in Australia to improve timely and accurate diagnosis and treatment patterns. The lung cancer multidisciplinary team (MDT) is critical to consistency of evidence-based diagnosis and treatment and can improve patient survival. We aimed to review current patterns of care and clinical practice recommendations for stage III NSCLC across Australia and identify opportunities to improve practice in referral, diagnosis and treatment pathways.

Rationale for Combining Radiotherapy and Immune Checkpoint Inhibition for Patients With Hypoxic Tumors

In order to compensate for the increased oxygen consumption in growing tumors, tumors need angiogenesis and vasculogenesis to increase the supply. Insufficiency in this process or in the microcirculation leads to hypoxic tumor areas with a significantly reduced pO2, which in turn leads to alterations in the biology of cancer cells as well as in the tumor microenvironment. Cancer cells develop more aggressive phenotypes, stem cell features and are more prone to metastasis formation and migration. In addition, intratumoral hypoxia confers therapy resistance, specifically radioresistance. Reactive oxygen species are crucial in fixing DNA breaks after ionizing radiation. Thus, hypoxic tumor cells show a two- to threefold increase in radioresistance. The microenvironment is enriched with chemokines (e.g., SDF-1) and growth factors (e.g., TGFβ) additionally reducing radiosensitivity. During recent years hypoxia has also been identified as a major factor for immune suppression in the tumor microenvironment. Hypoxic tumors show increased numbers of myeloid derived suppressor cells (MDSCs) as well as regulatory T cells (Tregs) and decreased infiltration and activation of cytotoxic T cells. The combination of radiotherapy with immune checkpoint inhibition is on the rise in the treatment of metastatic cancer patients, but is also tested in multiple curative treatment settings. There is a strong rationale for synergistic effects, such as increased T cell infiltration in irradiated tumors and mitigation of radiation-induced immunosuppressive mechanisms such as PD-L1 upregulation by immune checkpoint inhibition. Given the worse prognosis of patients with hypoxic tumors due to local therapy resistance but also increased rate of distant metastases and the strong immune suppression induced by hypoxia, we hypothesize that the subgroup of patients with hypoxic tumors might be of special interest for combining immune checkpoint inhibition with radiotherapy.

Combining Radiation and Immune Checkpoint Blockade in the Treatment of Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a significant cause of morbidity and mortality worldwide. Current treatment options, even though potentially curative, have many limitations including a high rate of complications. Over the past few years immune checkpoint inhibitors (ICI) targeting cytotoxic lymphocyte antigen-4 (CTLA-4), programmed cell death protein 1 (PD-1), and programmed cell death ligand 1 (PD-L1) have changed treatment paradigms in many malignancies and are currently under investigation in HNSCC as well. Despite improvements in treatment outcomes and the implementation of combined modality approaches long-term survival rates in patients with locally advanced HNSCC remain suboptimal. Accumulating evidence suggests that under certain conditions, radiation may be delivered in conjunction with ICI to augment efficacy. In this review, we will discuss the immune modulating mechanisms of ICI and radiation, how changing the dose, fractionation, and field of radiation may alter the tumor microenvironment (TME), and how these two treatment modalities may work in concert to generate durable treatment responses against HNSCC.

Synergistic effect of immunotherapy and radiotherapy in non-small cell lung cancer: current clinical trials and prospective challenges

Lately, the success of ICIs has drastically changed the landscape of cancer treatment, and several immune checkpoint inhibitors (ICIs) have been approved by the US Food and Drug Administration (FDA) for advanced non-small cell lung cancer (NSCLC). However, numerous patients are resistant to ICIs and require additional procedures for better efficacy results. Thus, combination therapy is urgently needed to strengthen the anti-tumor immunity. A variety of preclinical and clinical studies combining ICIs with radiotherapy (RT) have demonstrated that the combination could induce synergistic effects, as RT overcomes the resistance to ICIs. However, the underlying mechanism of the synergistic effect and the optimal arrangement of the combination therapy are indecisive now. Hence, this review was conducted to provide an update on the current clinical trial results and highlighted the ongoing trials. We also discussed the optimal parameters in clinical trials, including radiation dose, radiation fractionation, radiation target field, and sequencing of combination therapy. In this review, we found that combination therapy showed stronger anti-tumor immunity with tolerable toxicities in clinical trials. However, the best combination mode and potential biomarkers for the target patients in combination therapy are still unclear.

JAVELIN Head and Neck 100: a Phase III trial of avelumab and chemoradiation for locally advanced head and neck cancer

Chemoradiotherapy (CRT) is the standard of care for locoregionally advanced squamous cell carcinomas of the head and neck (HNSCC). The immune checkpoint inhibitors nivolumab and pembrolizumab were recently approved by the US FDA for treatment of recurrent or metastatic HNSCC that are refractory to platinum chemotherapy. However, prospective studies incorporating immune checkpoint inhibitors in the definitive management of poor prognosis, nonmetastatic, locoregionally advanced HNSCC are lacking. The JAVELIN Head and Neck 100 study is a multinational, Phase III, double-blind, placebo-controlled, randomized clinical trial assessing the efficacy of avelumab, a PD-L1 inhibitor, in combination with CRT compared with placebo in combination with CRT for high-risk HNSCC.

Trial registration: Javelin Head and Neck 100; NCT 02952586.

Clinical significance of pretreatment tumor growth rate for locally advanced non-small cell lung cancer

Background

Locally advanced non-small cell lung cancer (NSCLC) may exhibit significant tumor growth before the initiation of definitive chemoradiation therapy (CRT). We thus investigated the prognostic value of pretreatment tumor growth rate as measured by specific growth rate (SGR).

Methods

We conducted a retrospective review of 42 patients with locally advanced NSCLC treated with definitive concurrent CRT. For each patient, we contoured the primary gross tumor volume (GTV) on the pretreatment diagnostic chest computed tomography (CT) scan and the radiation therapy (RT) planning CT scan. We then calculated SGR based on the primary GTV from each scan and the time interval between scans. We used log-rank tests and univariate Cox regression models to quantify differences in progression-free survival (PFS), overall survival (OS) and recurrence based on SGR.

Results

We divided patients into two groups for analysis: those with an SGR greater than or equal to the upper tercile value of 0.94%/day (high SGR) and those with SGR less than 0.94%/day (low SGR). Patients with high SGRs versus low SGRs experienced inferior PFS (median, 5.6 vs. 13.6 months, P=0.016), without a significant difference in OS. The inferior PFS in the high SGR group persisted on multivariate analysis [adjusted hazard ratio (HR) 2.37, 95% confidence interval (CI): 1.07-5.25, P=0.034]. The risk of distant recurrence was higher in the high SGR group (HR 2.62, 95% CI: 1.08-6.38, P=0.033), but there was no difference in the risk of locoregional recurrence between groups.

Conclusions

Pretreatment SGR was associated with inferior PFS and distant control among patients with locally advanced NSCLC treated with concurrent CRT. Further studies in larger populations may aid in elucidating optimal SGR cut-off points for risk stratification.

Unmet Clinical Need in the Management of Locally Advanced Unresectable Lung Cancer: Treatment Strategies to Improve Patient Outcomes

Stage III locally advanced non-small cell lung cancer (LA NSCLC) comprises the most heterogeneous group of patients, accounts for one-third of patients with lung cancer, and is unresectable at presentation. Multiple treatment approaches have evolved over the past few decades focusing on timing of chemoradiation (concurrent vs. sequential) and sequencing of therapy (induction vs. consolidation). Concurrent chemoradiation (CCRT) emerged as the standard of care for the majority of the patients worldwide. Despite improvements in median and overall survival (OS) using the concurrent approach, the rate of distant failure remains high. Consolidation with chemotherapy or targeted agents, adding more radiation dose, or induction chemotherapy did not improve OS. With continued research on defining optimal radiation doses and schedules and integrating novel systemic agents, immunotherapy consolidation has renewed optimism. Synergistic use of radiation and immunotherapy can prevent micrometastatic disease and reduce local failure and may have an abscopal effect in addition to survival benefits. The PACIFIC study reported an absolute progression-free survival benefit of 11.2 months with durvalumab consolidation after standard CCRT compared with placebo. The OS data with durvalumab consolidation are encouraging. Durvalumab is the only approved immunotherapy for unresectable stage III LA NSCLC. Improved survival confirms the definitive role of durvalumab as an effective adjuvant therapy after CCRT with no new safety signals. However, the potential mechanisms driving interaction between immunotherapy and chemoradiotherapy require definitive investigation. These mechanisms may help define the timing of immunotherapy initiation as neoadjuvant, adjuvant, or consolidation and maintenance therapy after progression. FUNDING: AstraZeneca Pharma India Limited.

Rethinking pulmonary toxicity in advanced non-small cell lung cancer in the era of combining anti-PD-1/PD-L1 therapy with thoracic radiotherapy

The combination of programmed cell death 1/programmed cell death ligand 1 blockade and thoracic radiotherapy has become the new standard of care in the treatment of locally advanced non-small-cell lung cancer. The information regarding the pulmonary safety of such therapy remains limited to mostly retrospective studies and case reports with a small portion of data from prospective clinical trials. By analyzing the underlying mechanisms of interactions between radiation and immunotherapy from preclinical data and summarizing safety data from relevant clinical studies with pulmonary toxicity, we believe that longer and rigorous follow-up is warranted, to determine if the combination of such modalities is appropriate for patients without risking undue toxicity.

Radiotherapy toxicity

Radiotherapy is used in >50% of patients with cancer, both for curative and palliative purposes. Radiotherapy uses ionizing radiation to target and kill tumour tissue, but normal tissue can also be damaged, leading to toxicity. Modern and precise radiotherapy techniques, such as intensity-modulated radiotherapy, may prevent toxicity, but some patients still experience adverse effects. The physiopathology of toxicity is dependent on many parameters, such as the location of irradiation or the functional status of organs at risk. Knowledge of the mechanisms leads to a more rational approach for controlling radiotherapy toxicity, which may result in improved symptom control and quality of life for patients. This improved quality of life is particularly important in paediatric patients, who may live for many years with the long-term effects of radiotherapy. Notably, signs and symptoms occurring after radiotherapy may not be due to the treatment but to an exacerbation of existing conditions or to the development of new diseases. Although differential diagnosis may be difficult, it has important consequences for patients.

Role of Radiation Therapy in Modulation of the Tumor Stroma and Microenvironment

In recent decades, there has been substantial growth in our understanding of the immune system and its role in tumor growth and overall survival. A central finding has been the cross-talk between tumor cells and the surrounding environment or stroma. This tumor stroma, comprised of various cells, and extracellular matrix (ECM), has been shown to aid in suppressing host immune responses against tumor cells. Through immunosuppressive cytokine secretion, metabolic alterations, and other mechanisms, the tumor stroma provides a complex network of safeguards for tumor proliferation. With recent advances in more effective, localized treatment, radiation therapy (XRT) has allowed for strategies that can effectively alter and ablate tumor stromal tissue. This includes promoting immunogenic cell death through tumor antigen release to increasing immune cell trafficking, XRT has a unique advantage against the tumoral immune evasion mechanisms that are orchestrated by stromal cells. Current studies are underway to elucidate pathways within the tumor stroma as potential targets for immunotherapy and chemoradiation. This review summarizes the effects of tumor stroma in tumor immune evasion, explains how XRT may help overcome these effects, with potential combinatorial approaches for future treatment modalities.

The immunological consequences of radiation-induced DNA damage

Historically, our understanding of the cytotoxicity of radiation has centred on tumour cell-autonomous mechanisms of cell death. Here, tumour cell death occurs when a threshold number of radiation-induced non-reparable double-stranded DNA breaks is exceeded. However, in recent years, the importance of immune mechanisms of cell death has been increasingly recognised, as well as the impact of radiotherapy on non-malignant cellular components of the tumour microenvironment. Conserved antiviral pathways that detect foreign nucleic acid in the cytosol and drive downstream interferon (IFN) responses via the cyclic guanosine monophosphate-adenosine monophosphate synthase/stimulator of IFN genes (cGAS/STING) pathway are key components of the immune response to radiation-induced DNA damage. In preclinical models, acute induction of a type 1 IFN response is important for both direct and abscopal tumour responses to radiation. Inhibitors of the DNA damage response show promise in augmenting this inflammatory IFN response. However, a substantial proportion of tumours show chronic IFN signalling prior to radiotherapy, which paradoxically drives immunosuppression. This chronic IFN signalling leads to treatment resistance, and heterotypic interactions between stromal fibroblasts and tumour cells contribute to an aggressive tumour phenotype. The effect of radiotherapy on myeloid cell populations, particularly tumour-associated macrophages, has an additional impact on the immune tumour microenvironment. It is not yet clear how the above preclinical findings translate into a human context. Human tumours show greater intratumoural genomic heterogeneity and more variable levels of chromosomal instability than experimental murine models. High-quality translational studies of immunological changes occurring during radiotherapy that incorporate intrinsic tumour biology will enable a better understanding of the immunological consequences of radiation-induced DNA damage in patients. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Perspectives on treatment advances for stage III locally advanced unresectable non-small-cell lung cancer

For more than a decade, there has been no improvement in outcomes for patients with unresectable locally advanced (la) non-small-cell lung cancer (nsclc). The standard treatment in that setting is definitive concurrent chemotherapy and radiation (ccrt). Although the intent of treatment is curative, most patients rapidly progress, and their prognosis is poor, with a 5-year overall survival (os) rate in the 15%-25% range. Those patients therefore represent a critical unmet need, warranting expedited approval of, and access to, new treatments that can improve outcomes. The pacific trial, which evaluated durvalumab consolidation therapy after ccrt in unresectable la nsclc, demonstrated a statistically significant and clinically meaningful improvement in progression-free survival (pfs) and a significant improvement in os. Durvalumab thus fills a critical unmet need in the setting of unresectable la nsclc and provides a new option for patients treated with curative intent. Here, we review the treatment of unresectable la nsclc, with a focus on the effect of the clinical data for durvalumab.

Early fatal hemoptysis after first-dose, first-line pembrolizumab in a central lung cancer: did tumor shrinkage matter?

A patient diagnosed with centrally located advanced lung adenocarcinoma with signs of large vessels infiltration, strongly expressing PD-L1, was candidate to first-line pembrolizumab. He had not complained of any bleeding manifestation before immunotherapy. 5 days after the first dose of pembrolizumab, the patient experienced massive, fatal hemoptysis. Given the central localization of the tumor and the strong PD-L1 expression, a contribution of rapid disease shrinkage is envisaged in determining the fatal hemorrhagic event. An attentive clinical attitude should be dedicated in centrally located and vessel-infiltrating tumors strongly expressing PD-L1 and candidate to anti-PD-1/PD-L1 agents.

Immune Checkpoint Inhibitors and Radiotherapy in NSCLC Patients: Not Just a Fluke

The discovery of immune checkpoint inhibitors (ICIs) such as programmed cell death protein 1 (PD-1) inhibitors, nivolumab and pembrolizumab, and programmed cell death ligand 1 (PD-L1) inhibitors, atezolizumab and durvalumab, has revolutionized the treatment of advanced non-small cell lung cancer (NSCLC). Concurrent radiotherapy (RT) is of particular interest with regard to the potential role for this combination in many settings. The purpose of this commentary is to evaluate the potential for the combination of immune checkpoint inhibitors and radiotherapy, including analysis of studies that have considered this combination in various settings.

Time for radioimmunotherapy: an overview to bring improvements in clinical practice

Harnessing the patient's own immune system against an established cancer has proven to be a successful strategy. Within the last years, several antibodies blocking critical "checkpoints" that control the activation of T cells, the immune cells able to kill cancer cells, have been approved for the use in patients with different tumours. Unfortunately, these cases remain a minority. Over the last years, radiotherapy has been reported as a means to turn a patient's own tumour into an in situ vaccine and generate anti-tumour T cells in patients who lack sufficient anti-tumour immunity. Indeed, review data show that the strategy of blocking multiple selected immune inhibitory targets in combination with radiotherapy has the potential to unleash powerful anti-tumour responses and improve the outcome of metastatic solid tumours. Here, we review the principal tumours where research in this field has led to new knowledge and where radioimmunotherapy becomes a reality.

Updates in Local-Regionally Advanced Non-Small Cell Lung Cancer

The landscape for therapy in local-regionally advanced non-small cell lung cancer (NSCLC) has shifted dramatically in the last year as a result of the PACIFIC trial, which demonstrated a significant survival benefit with the addition of 1 year of durvalumab after concurrent chemoradiation. This is a new standard of care for unresectable local-regionally advanced NSCLC and is the first trial to show that immunotherapy can increase survival in earlier-stage NSCLC. Several clinical trials are underway or in development to explore the role of adding immunotherapy to concurrent chemoradiation, followed by a year of immunotherapy or to even replace chemotherapy in this treatment paradigm. In resectable disease, adjuvant chemotherapy is still the standard of care for stage IB (tumors ≥ 4 cm) through stage III disease. However, new studies are investigating the role of adding immunotherapy to neoadjuvant chemotherapy or as adjuvant therapy for 1 year after resection. Molecular profiling for early-stage disease is not currently the standard of care, but several national clinical trials are studying the benefit of adding adjuvant-targeted therapies. This article will detail the current standard practices in early-stage and local-regionally advanced NSCLC and describe the evolving strategies that are under investigation that may further refine our current practice.

Durvalumab for stage III non-small-cell lung cancer patients: clinical evidence and real-world experience

Stage III non-small cell lung cancer (NSCLC) has a dismal prognosis, with only 15-20% of patients alive at 5 years after concomitant chemo-radiotherapy, which represents the standard treatment. Targeting immune-checkpoint inhibitors represents a standard option for advanced NSCLC. Improvements in understanding of the immune profile of NSCLC has led to the development of immunotherapeutic strategies, including inhibitory molecules responsible for abrogating an anticancer immune response such as programmed cell-death 1 and programmed cell-death ligand 1. A recently published phase III trial (PACIFIC) showed for the first time an improved overall survival in stage III NSCLC patients with consolidative durvalumab. The aim of this review is to summarize and discuss the clinical evidence for the use of durvalumab in stage III NSCLC, with a brief overview on future perspectives in this setting.

Rationale for combination of radiation therapy and immune checkpoint blockers to improve cancer treatment

Radiation therapy for cancer is considered to be immunosuppressive. However, the cellular response after radiation therapy may stimulate or suppress an immune response. The effect may vary with the tumor type and occasionally tumor regressions have been observed outside the irradiated volume, both in animal studies and in the clinic. A renewed interest in the role of immunity for the observed effect of radiation came with the current recognized role of immune checkpoint blockers (ICBs) for control of selected cancer types. We therefore here review preclinical studies and clinical reports on the interaction of ICBs and radiation as a basis for further clinical trials. Some tumor types where the combination of these modalities seems especially promising are also proposed.

SEOM clinical guidelines for the treatment of non-small cell lung cancer (2018)

Non-small cell lung cancer (NSCLC) accounts for up to 85% of all lung cancers. The last few years have seen the development of a new staging system, diagnostic procedures such as liquid biopsy, treatments like immunotherapy, as well as deeper molecular knowledge; so, more options can be offered to patients with driver mutations. Groups with specific treatments account for around 25% and demonstrate significant increases in overall survival, and in some subgroups, it is important to evaluate each treatment alternative in accordance with scientific evidence, and even more so with immunotherapy. New treatments similarly mean that we must reconsider what should be done in oligometastatic disease where local treatment attains greater value.

From Tumor Immunology to Immunotherapy in Gastric and Esophageal Cancer

Esophageal and gastric cancers represent tumors with poor prognosis. Unfortunately, radiotherapy, chemotherapy, and targeted therapy have made only limited progress in recent years in improving the generally disappointing outcome. Immunotherapy with checkpoint inhibitors is a novel treatment approach that quickly entered clinical practice in malignant melanoma and renal cell cancer, but the role in esophageal and gastric cancer is still poorly defined. The principal prognostic/predictive biomarkers for immunotherapy efficacy currently considered are PD-L1 expression along with defects in mismatch repair genes resulting in microsatellite instability (MSI-H) phenotype. The new molecular classification of gastric cancer also takes these factors into consideration. Available reports regarding PD-1, PD-L1, PD-L2 expression and MSI status in gastric and esophageal cancer are reviewed to summarize the clinical prognostic and predictive role together with potential clinical implications. The most important recently published clinical trials evaluating checkpoint inhibitor efficacy in these tumors are also summarized.

Radiotherapy as a New Player in Immuno-Oncology

Recent development in radiation biology has revealed potent immunogenic properties of radiotherapy in cancer treatments. However, antitumor immune effects of radiotherapy are limited by the concomitant induction of radiation-dependent immunosuppressive effects. In the growing era of immunotherapy, combining radiotherapy with immunomodulating agents has demonstrated enhancement of radiation-induced antitumor immune activation that correlated with improved treatment outcomes. Yet, how to optimally deliver combination therapy regarding dose-fractionation and timing of radiotherapy is largely unknown. Future prospective testing to fine-tune this promising combination of radiotherapy and immunotherapy is warranted.

Radiation, Immune Checkpoint Blockade and the Abscopal Effect: A Critical Review on Timing, Dose and Fractionation

The combination of radiation and immunotherapy is currently an exciting avenue of pre-clinical and clinical investigation. The synergy between these two treatment modalities has the potential to expand the role of radiation from a purely local therapy, to a role in advanced and metastatic disease. Tumor regression outside of the irradiated field, known as the abscopal effect, is a recognized phenomenon mediated by lymphocytes and enhanced by checkpoint blockade. In this review, we summarize the known mechanistic data behind the immunostimulatory effects of radiation and how this is enhanced by immunotherapy. We also provide pre-clinical data supporting specific radiation timing and optimal dose/fractionation for induction of a robust anti-tumor immune response with or without checkpoint blockade. Importantly, these data are placed in a larger context of understanding T-cell exhaustion and the impact of immunotherapy on this phenotype. We also include relevant pre-clinical studies done in non-tumor systems. We discuss the published clinical trials and briefly summarize salient case reports evaluating the abscopal effect. Much of the data discussed here remains at the preliminary stage, and a number of interesting avenues of research remain under investigation.

Combination of novel systemic agents and radiotherapy for solid tumors - part I: An AIRO (Italian association of radiotherapy and clinical oncology) overview focused on treatment efficacy

Over the past century, technologic advances have promoted the evolution of radiation therapy into a precise treatment modality allowing for the maximal administration of dose to tumors while sparing normal tissues. In parallel with this technological maturation, the rapid expansion in understanding the basic biology and heterogeneity of cancer has led to the development of several compounds that target specific pathways. Many of them are in advanced steps of clinical development for combination treatments with radiotherapy, and can be incorporated into radiation oncology practice for a personalized approach to maximize the therapeutic gain. This review describes the rationale for combining novel agents with radiation, and provides an overview of the current landscape focused on treatment efficacy.

Combination of novel systemic agents and radiotherapy for solid tumors - Part II: An AIRO (Italian association of radiotherapy and clinical oncology) overview focused on treatment toxicity

Clinical development and use of novel systemic agents in combination with radiotherapy (RT) is at nowadays most advanced in the field of treatment of solid tumors. Although for many of these substances preclinical studies provide sufficient evidences on their principal capability to enhance radiation effects, the majority of them have not been investigated in even phase I clinical trials for safety in the context of RT. In clinical practice, unexpected acute and late side effects may emerge especially in combination with RT. As a matter of fact, despite combined modality treatment holds potential for enhancing the therapeutic ratio, some concerns are raised from the lack of high-quality clinical data to guide the care of patients who are treated with novel compounds in conjunction with RT. The aim of this review is to provide, from a radio-oncological point of view, an overview of the most advanced combined treatment concepts for solid tumors focusing on treatment toxicity.

Proton Therapy in Non-small Cell Lung Cancer

OPINION STATEMENT

Non-small cell lung cancer (NSCLC) accounts for 85% of new lung cancer cases and has 5-year survival rates ranging from 92% in early-stage disease to as low as 13% in locally advanced cases. Radiation therapy is a key component in the treatment repertoire for NSCLC, where it is currently used alone or in combinations with chemotherapy and surgery. Despite the broad use of modern photon radiation techniques, as many as 25% of patients experience isolated locoregional recurrences, and toxicity has been proven to be a limiting factor in many cases. Proton beam therapy (PBT) has emerged as a potential solution to improve upon clinical outcomes in both early-stage and locally advanced disease. The proton beam allows for a sharp dose build-up and drop-off, which is particularly important in lung cancer where nearby structures include the heart, spinal cord, esophagus, and uninvolved lung. There are now numerous studies showing dosimetric advantages of PBT in early and locally advanced NSCLC, particularly in the heart and lung doses. Randomized data comparing clinical outcomes between proton and photon radiation are limited to a small number of studies. Despite early results suggesting improvements or at least comparable outcomes with PBT, the most recent randomized comparisons have failed to show significant differences in toxicity and local control between photon and proton therapy. As newer PBT techniques (e.g., intensity-modulated proton therapy) are increasingly utilized, more dramatic improvements in tumor control and toxicity may be demonstrated. It is also important to recognize that there may be certain subpopulations in which the benefits of proton therapy are greater, such as central early-stage tumors, previously irradiated tumors, and locally advanced tumors, while others may best be treated with traditional photon techniques. As immunotherapy becomes more prevalent in the treatment of NSCLC, improving local control and limiting the toxicity contributed by radiation will be increasingly important. The unique dosimetric advantages of PBT may allow for tumor dose escalation while maintaining normal tissue doses to improve local control, or treating the tumor to the standard dose while decreasing normal tissue doses to improve toxicity. Finally, given the high costs of proton therapy, where low insurance approval rates have limited trial enrollment, it will be important to determine the overall cost-benefit ratio.

Immunotherapy for non-small cell lung cancers: biomarkers for predicting responses and strategies to overcome resistance

Recent breakthroughs in targeted therapy and immunotherapy have revolutionized the treatment of lung cancer, the leading cause of cancer-related deaths in the United States and worldwide. Here we provide an overview of recent progress in immune checkpoint blockade therapy for treatment of non-small cell lung cancer (NSCLC), and discuss biomarkers associated with the treatment responses, mechanisms underlying resistance and strategies to overcome resistance. The success of immune checkpoint blockade therapies is driven by immunogenicity of tumor cells, which is associated with mutation burden and neoantigen burden in cancers. Lymphocyte infiltration in cancer tissues and interferon-γ-induced PD-L1 expression in tumor microenvironments may serve as surrogate biomarkers for adaptive immune resistance and likelihood of responses to immune checkpoint blockade therapy. In contrast, weak immunogenicity of, and/or impaired antigen presentation in, tumor cells are primary causes of resistance to these therapies. Thus, approaches that increase immunogenicity of cancer cells and/or enhance immune cell recruitment to cancer sites will likely overcome resistance to immunotherapy.